Printed metal gasket

ABSTRACT

Techniques and devices are provided for attaching a die to a metal manifold. A metal-containing ink is used to deposit a metal trace on the die and thereby to form a gasket, after which the die is compressed against the manifold to form a sealed connection between the two.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.16/245,517, filed on Jan. 11, 2019, which is a non-provisional andclaims the priority benefit of U.S. Patent Application Ser. No.62/615,993, filed Jan. 11, 2018, the entire contents of each of whichare incorporated herein by reference.

FIELD

The present invention relates to systems and techniques for printing ametal gasket for use in devices for fabricating organic light emittingdiodes, and devices including the same.

BACKGROUND

Opto-electronic devices that make use of organic materials are becomingincreasingly desirable for a number of reasons. Many of the materialsused to make such devices are relatively inexpensive, so organicopto-electronic devices have the potential for cost advantages overinorganic devices. In addition, the inherent properties of organicmaterials, such as their flexibility, may make them well suited forparticular applications such as fabrication on a flexible substrate.Examples of organic opto-electronic devices include organic lightemitting diodes/devices (OLEDs), organic phototransistors, organicphotovoltaic cells, and organic photodetectors. For OLEDs, the organicmaterials may have performance advantages over conventional materials.For example, the wavelength at which an organic emissive layer emitslight may generally be readily tuned with appropriate dopants.

OLEDs make use of thin organic films that emit light when voltage isapplied across the device. OLEDs are becoming an increasinglyinteresting technology for use in applications such as flat paneldisplays, illumination, and backlighting. Several OLED materials andconfigurations are described in U.S. Pat. Nos. 5,844,363, 6,303,238, and5,707,745, which are incorporated herein by reference in their entirety.

One application for phosphorescent emissive molecules is a full colordisplay. Industry standards for such a display call for pixels adaptedto emit particular colors, referred to as “saturated” colors. Inparticular, these standards call for saturated red, green, and bluepixels. Alternatively the OLED can be designed to emit white light. Inconventional liquid crystal displays emission from a white backlight isfiltered using absorption filters to produce red, green and blueemission. The same technique can also be used with OLEDs. The white OLEDcan be either a single EML device or a stack structure. Color may bemeasured using CIE coordinates, which are well known to the art.

As used herein, the term “organic” includes polymeric materials as wellas small molecule organic materials that may be used to fabricateorganic opto-electronic devices. “Small molecule” refers to any organicmaterial that is not a polymer, and “small molecules” may actually bequite large. Small molecules may include repeat units in somecircumstances. For example, using a long chain alkyl group as asubstituent does not remove a molecule from the “small molecule” class.Small molecules may also be incorporated into polymers, for example as apendent group on a polymer backbone or as a part of the backbone. Smallmolecules may also serve as the core moiety of a dendrimer, whichconsists of a series of chemical shells built on the core moiety. Thecore moiety of a dendrimer may be a fluorescent or phosphorescent smallmolecule emitter. A dendrimer may be a “small molecule,” and it isbelieved that all dendrimers currently used in the field of OLEDs aresmall molecules.

As used herein, “top” means furthest away from the substrate, while“bottom” means closest to the substrate. Where a first layer isdescribed as “disposed over” a second layer, the first layer is disposedfurther away from substrate. There may be other layers between the firstand second layer, unless it is specified that the first layer is “incontact with” the second layer. For example, a cathode may be describedas “disposed over” an anode, even though there are various organiclayers in between.

As used herein, “solution processible” means capable of being dissolved,dispersed, or transported in and/or deposited from a liquid medium,either in solution or suspension form.

A ligand may be referred to as “photoactive” when it is believed thatthe ligand directly contributes to the photoactive properties of anemissive material. A ligand may be referred to as “ancillary” when it isbelieved that the ligand does not contribute to the photoactiveproperties of an emissive material, although an ancillary ligand mayalter the properties of a photoactive ligand.

As used herein, and as would be generally understood by one skilled inthe art, a first “Highest Occupied Molecular Orbital” (HOMO) or “LowestUnoccupied Molecular Orbital” (LUMO) energy level is “greater than” or“higher than” a second HOMO or LUMO energy level if the first energylevel is closer to the vacuum energy level. Since ionization potentials(IP) are measured as a negative energy relative to a vacuum level, ahigher HOMO energy level corresponds to an IP having a smaller absolutevalue (an IP that is less negative). Similarly, a higher LUMO energylevel corresponds to an electron affinity (EA) having a smaller absolutevalue (an EA that is less negative). On a conventional energy leveldiagram, with the vacuum level at the top, the LUMO energy level of amaterial is higher than the HOMO energy level of the same material. A“higher” HOMO or LUMO energy level appears closer to the top of such adiagram than a “lower” HOMO or LUMO energy level.

As used herein, and as would be generally understood by one skilled inthe art, a first work function is “greater than” or “higher than” asecond work function if the first work function has a higher absolutevalue. Because work functions are generally measured as negative numbersrelative to vacuum level, this means that a “higher” work function ismore negative. On a conventional energy level diagram, with the vacuumlevel at the top, a “higher” work function is illustrated as furtheraway from the vacuum level in the downward direction. Thus, thedefinitions of HOMO and LUMO energy levels follow a different conventionthan work functions.

More details on OLEDs, and the definitions described above, can be foundin U.S. Pat. No. 7,279,704, which is incorporated herein by reference inits entirety.

SUMMARY

According to an embodiment, a method of fabricating a device comprisinga die and a metal manifold is provided, in which a metal-containing inkis deposited in one or more traces around one or more vias on a die toform a gasket. The gasket is then placed in direct physical contact witha metal manifold to which the die is to be sealed and compressed againstthe metal manifold to form a sealed connection between the one or morevias and one or more corresponding channels in the metal manifold. Thetraces may form a closed contour around at least one of the one or morevias. The die may include multiple vias, and the method may furtherinclude depositing a plurality of non-intersecting traces including theone or more traces, each trace of the plurality of traces depositedaround one or more of the plurality of vias. Alternatively, the tracesmay be deposited such that at least two of the plurality of tracesintersect. The metal-containing ink may include one or more compoundssuch as a suspension of metallic nanoparticles in an organic solvent;and a solution of organometallic precursors. The metal may be, forexample, silver, gold, copper, and/or titanium. The gasket may be placedto an accuracy of less than 10 μm and the gasket may have a thickness ofnot more than 100 μm.

According to an embodiment, a device is provided that includes amanifold and a die comprising one or more vias, with a metal gasketdisposed on and non-removably attached to a surface of the die aroundthe one or more vias, deposited via a metal-containing ink. The gasketremovably connects the die to the metal manifold. The gasket may includeone or more closed contour(s) around the one or more vias, which may beintersecting or non-intersecting. The die may be removable from themanifold solely by removal of a compressive force that removablyattaches the gasket and die to the manifold.

According to an embodiment, a method of attaching two components viametal gasket is provided that includes depositing a metal-containing inkon a first component of a device to form a gasket, placing the gasket indirect physical contact with a second component of a device to which thefirst component is to be attached, and applying a compressive force tothe first component against the second component to form a sealedconnection between the first component and the second component. Thefirst component may be removable from the second component solely byremoval of the compressive force.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an organic light emitting device.

FIG. 2 shows an inverted organic light emitting device that does nothave a separate electron transport layer.

FIG. 3 shows a cross-section of an illustrative OVJP print headcontaining a micronozzle die sealed to a die clamp using conventionalarrangements.

FIG. 4A shows an example of a joining surface of a die featuring aprinted metal gasket according to an embodiment disclosed herein.

FIG. 4B shows a cross section of a micronozzle array sealed to a dieclamp using a printed metal gasket according to an embodiment disclosedherein.

FIGS. 5A, 5B, and 5C show examples of multiple metal traces forminggasket seals on the surface of a die according to an embodimentdisclosed herein.

FIG. 6 shows an example of a Si die with a printed metal gasket incross-section, illustrating thin film layers for adhesion promotionaccording to an embodiment disclosed herein.

FIGS. 7A and 7B show cross sections of example gland designs on a clampsurface suitable for use with printed metal gaskets according toembodiments disclosed herein.

FIGS. 8A and 8B show a dimensioned drawing a die containing amicronozzle array for use with printed metal gaskets according to anembodiment disclosed herein.

FIG. 9 shows the path and thickness of a silver gasket printed on a dieaccording to an embodiment disclosed herein.

FIG. 10 shows the cross-sectional thickness profile of a printed metalgasket on a die according to an embodiment disclosed herein.

DETAILED DESCRIPTION

Generally, an OLED comprises at least one organic layer disposed betweenand electrically connected to an anode and a cathode. When a current isapplied, the anode injects holes and the cathode injects electrons intothe organic layer(s). The injected holes and electrons each migratetoward the oppositely charged electrode. When an electron and holelocalize on the same molecule, an “exciton,” which is a localizedelectron-hole pair having an excited energy state, is formed. Light isemitted when the exciton relaxes via a photoemissive mechanism. In somecases, the exciton may be localized on an excimer or an exciplex.Non-radiative mechanisms, such as thermal relaxation, may also occur,but are generally considered undesirable.

The initial OLEDs used emissive molecules that emitted light from theirsinglet states (“fluorescence”) as disclosed, for example, in U.S. Pat.No. 4,769,292, which is incorporated by reference in its entirety.Fluorescent emission generally occurs in a time frame of less than 10nanoseconds.

More recently, OLEDs having emissive materials that emit light fromtriplet states (“phosphorescence”) have been demonstrated. Baldo et al.,“Highly Efficient Phosphorescent Emission from OrganicElectroluminescent Devices,” Nature, vol. 395, 151-154, 1998;(“Baldo-I”) and Baldo et al., “Very high-efficiency green organiclight-emitting devices based on electrophosphorescence,” Appl. Phys.Lett., vol. 75, No. 3, 4-6 (1999) (“Baldo-II”), are incorporated byreference in their entireties. Phosphorescence is described in moredetail in U.S. Pat. No. 7,279,704 at cols. 5-6, which are incorporatedby reference.

FIG. 1 shows an organic light emitting device 100. The figures are notnecessarily drawn to scale. Device 100 may include a substrate 110, ananode 115, a hole injection layer 120, a hole transport layer 125, anelectron blocking layer 130, an emissive layer 135, a hole blockinglayer 140, an electron transport layer 145, an electron injection layer150, a protective layer 155, a cathode 160, and a barrier layer 170.Cathode 160 is a compound cathode having a first conductive layer 162and a second conductive layer 164. Device 100 may be fabricated bydepositing the layers described, in order. The properties and functionsof these various layers, as well as example materials, are described inmore detail in U.S. Pat. No. 7,279,704 at cols. 6-10, which areincorporated by reference.

More examples for each of these layers are available. For example, aflexible and transparent substrate-anode combination is disclosed inU.S. Pat. No. 5,844,363, which is incorporated by reference in itsentirety. An example of a p-doped hole transport layer is m-MTDATA dopedwith F₄-TCNQ at a molar ratio of 50:1, as disclosed in U.S. PatentApplication Publication No. 2003/0230980, which is incorporated byreference in its entirety. Examples of emissive and host materials aredisclosed in U.S. Pat. No. 6,303,238 to Thompson et al., which isincorporated by reference in its entirety. An example of an n-dopedelectron transport layer is BPhen doped with Li at a molar ratio of 1:1,as disclosed in U.S. Patent Application Publication No. 2003/0230980,which is incorporated by reference in its entirety. U.S. Pat. Nos.5,703,436 and 5,707,745, which are incorporated by reference in theirentireties, disclose examples of cathodes including compound cathodeshaving a thin layer of metal such as Mg:Ag with an overlyingtransparent, electrically-conductive, sputter-deposited ITO layer. Thetheory and use of blocking layers is described in more detail in U.S.Pat. No. 6,097,147 and U.S. Patent Application Publication No.2003/0230980, which are incorporated by reference in their entireties.Examples of injection layers are provided in U.S. Patent ApplicationPublication No. 2004/0174116, which is incorporated by reference in itsentirety. A description of protective layers may be found in U.S. PatentApplication Publication No. 2004/0174116, which is incorporated byreference in its entirety.

FIG. 2 shows an inverted OLED 200. The device includes a substrate 210,a cathode 215, an emissive layer 220, a hole transport layer 225, and ananode 230. Device 200 may be fabricated by depositing the layersdescribed, in order. Because the most common OLED configuration has acathode disposed over the anode, and device 200 has cathode 215 disposedunder anode 230, device 200 may be referred to as an “inverted” OLED.Materials similar to those described with respect to device 100 may beused in the corresponding layers of device 200. FIG. 2 provides oneexample of how some layers may be omitted from the structure of device100.

The simple layered structure illustrated in FIGS. 1 and 2 is provided byway of non-limiting example, and it is understood that embodiments ofthe invention may be used in connection with a wide variety of otherstructures. The specific materials and structures described areexemplary in nature, and other materials and structures may be used.Functional OLEDs may be achieved by combining the various layersdescribed in different ways, or layers may be omitted entirely, based ondesign, performance, and cost factors. Other layers not specificallydescribed may also be included. Materials other than those specificallydescribed may be used. Although many of the examples provided hereindescribe various layers as comprising a single material, it isunderstood that combinations of materials, such as a mixture of host anddopant, or more generally a mixture, may be used. Also, the layers mayhave various sublayers. The names given to the various layers herein arenot intended to be strictly limiting. For example, in device 200, holetransport layer 225 transports holes and injects holes into emissivelayer 220, and may be described as a hole transport layer or a holeinjection layer. In one embodiment, an OLED may be described as havingan “organic layer” disposed between a cathode and an anode. This organiclayer may comprise a single layer, or may further comprise multiplelayers of different organic materials as described, for example, withrespect to FIGS. 1 and 2.

Structures and materials not specifically described may also be used,such as OLEDs comprised of polymeric materials (PLEDs) such as disclosedin U.S. Pat. No. 5,247,190 to Friend et al., which is incorporated byreference in its entirety. By way of further example, OLEDs having asingle organic layer may be used. OLEDs may be stacked, for example asdescribed in U.S. Pat. No. 5,707,745 to Forrest et al, which isincorporated by reference in its entirety. The OLED structure maydeviate from the simple layered structure illustrated in FIGS. 1 and 2.For example, the substrate may include an angled reflective surface toimprove out-coupling, such as a mesa structure as described in U.S. Pat.No. 6,091,195 to Forrest et al., and/or a pit structure as described inU.S. Pat. No. 5,834,893 to Bulovic et al., which are incorporated byreference in their entireties.

In general, the various layers of OLEDs and similar devices describedherein may be deposited by any suitable method. For the organic layers,preferred methods include thermal evaporation, ink-jet, such asdescribed in U.S. Pat. Nos. 6,013,982 and 6,087,196, which areincorporated by reference in their entireties, organic vapor phasedeposition (OVPD), such as described in U.S. Pat. No. 6,337,102 toForrest et al., which is incorporated by reference in its entirety, anddeposition by organic vapor jet printing (OVJP), such as described inU.S. Pat. No. 7,431,968, which is incorporated by reference in itsentirety. Other suitable deposition methods include spin coating andother solution based processes. Solution based processes are preferablycarried out in nitrogen or an inert atmosphere. For the other layers,preferred methods include thermal evaporation. Preferred patterningmethods include deposition through a mask, cold welding such asdescribed in U.S. Pat. Nos. 6,294,398 and 6,468,819, which areincorporated by reference in their entireties, and patterning associatedwith some of the deposition methods such as ink jet and OVJD. Othermethods may also be used. The materials to be deposited may be modifiedto make them compatible with a particular deposition method. Forexample, substituents such as alkyl and aryl groups, branched orunbranched, and preferably containing at least 3 carbons, may be used insmall molecules to enhance their ability to undergo solution processing.Substituents having 20 carbons or more may be used, and 3-20 carbons isa preferred range. Materials with asymmetric structures may have bettersolution processibility than those having symmetric structures, becauseasymmetric materials may have a lower tendency to recrystallize.Dendrimer substituents may be used to enhance the ability of smallmolecules to undergo solution processing.

Some OLED structures and similar devices may further optionally comprisea barrier layer. One purpose of the barrier layer is to protect theelectrodes and organic layers from damaging exposure to harmful speciesin the environment including moisture, vapor and/or gases, etc. Thebarrier layer may be deposited over, under or next to a substrate, anelectrode, or over any other parts of a device including an edge. Thebarrier layer may comprise a single layer, or multiple layers. Thebarrier layer may be formed by various known chemical vapor depositiontechniques and may include compositions having a single phase as well ascompositions having multiple phases. Any suitable material orcombination of materials may be used for the barrier layer. The barrierlayer may incorporate an inorganic or an organic compound or both. Thepreferred barrier layer comprises a mixture of a polymeric material anda non-polymeric material as described in U.S. Pat. No. 7,968,146, PCTPat. Application Nos. PCT/US2007/023098 and PCT/US2009/042829, which areherein incorporated by reference in their entireties. To be considered a“mixture”, the aforesaid polymeric and non-polymeric materialscomprising the barrier layer should be deposited under the same reactionconditions and/or at the same time. The weight ratio of polymeric tonon-polymeric material may be in the range of 95:5 to 5:95. Thepolymeric material and the non-polymeric material may be created fromthe same precursor material. In one example, the mixture of a polymericmaterial and a non-polymeric material consists essentially of polymericsilicon and inorganic silicon.

Devices fabricated in accordance with embodiments of the invention canbe incorporated into a wide variety of electronic component modules (orunits) that can be incorporated into a variety of electronic products orintermediate components. Examples of such electronic products orintermediate components include display screens, lighting devices suchas discrete light source devices or lighting panels, etc. that can beutilized by the end-user product manufacturers. Such electroniccomponent modules can optionally include the driving electronics and/orpower source(s). Devices fabricated in accordance with embodiments ofthe invention can be incorporated into a wide variety of consumerproducts that have one or more of the electronic component modules (orunits) incorporated therein. A consumer product comprising an OLED thatincludes the compound of the present disclosure in the organic layer inthe OLED is disclosed. Such consumer products would include any kind ofproducts that include one or more light source(s) and/or one or more ofsome type of visual displays. Some examples of such consumer productsinclude flat panel displays, computer monitors, medical monitors,televisions, billboards, lights for interior or exterior illuminationand/or signaling, heads-up displays, fully or partially transparentdisplays, flexible displays, laser printers, telephones, mobile phones,tablets, phablets, personal digital assistants (PDAs), wearable devices,laptop computers, digital cameras, camcorders, viewfinders,micro-displays (displays that are less than 2 inches diagonal), 3-Ddisplays, virtual reality or augmented reality displays, vehicles, videowalls comprising multiple displays tiled together, theater or stadiumscreen, and a sign. Various control mechanisms may be used to controldevices fabricated in accordance with the present invention, includingpassive matrix and active matrix. Many of the devices are intended foruse in a temperature range comfortable to humans, such as 18 C to 30 C,and more preferably at room temperature (20-25 C), but could be usedoutside this temperature range, for example, from −40 C to 80 C.

The materials, structures, and techniques described herein may haveapplications in devices other than the fabrication of OLEDs. Forexample, other optoelectronic devices such as organic solar cells andorganic photodetectors may employ or be fabricated by the materials,structures, and techniques. More generally, organic devices, such asorganic transistors, may employ the materials, structures, andtechniques.

An OLED fabricated using devices and techniques disclosed herein mayhave one or more characteristics selected from the group consisting ofbeing flexible, being rollable, being foldable, being stretchable, andbeing curved, and may be transparent or semi-transparent. In someembodiments, the OLED further comprises a layer comprising carbonnanotubes.

In some embodiments, an OLED fabricated using devices and techniquesdisclosed herein further comprises a layer comprising a delayedfluorescent emitter. In some embodiments, the OLED comprises a RGB pixelarrangement or white plus color filter pixel arrangement. In someembodiments, the OLED is a mobile device, a hand held device, or awearable device. In some embodiments, the OLED is a display panel havingless than 10 inch diagonal or 50 square inch area. In some embodiments,the OLED is a display panel having at least 10 inch diagonal or 50square inch area. In some embodiments, the OLED is a lighting panel.

In some embodiments of the emissive region, the emissive region furthercomprises a host.

In some embodiments, the compound can be an emissive dopant. In someembodiments, the compound can produce emissions via phosphorescence,fluorescence, thermally activated delayed fluorescence, i.e., TADF (alsoreferred to as E-type delayed fluorescence), triplet-tripletannihilation, or combinations of these processes.

An OLED fabricated according to techniques and devices disclosed hereincan be incorporated into one or more of a consumer product, anelectronic component module, and a lighting panel. The organic layer canbe an emissive layer and the compound can be an emissive dopant in someembodiments, while the compound can be a non-emissive dopant in otherembodiments.

The organic layer can also include a host. In some embodiments, two ormore hosts are preferred. In some embodiments, the hosts used maybe a)bipolar, b) electron transporting, c) hole transporting or d) wide bandgap materials that play little role in charge transport. In someembodiments, the host can include a metal complex. The host can be aninorganic compound.

Combination with Other Materials

The materials described herein as useful for a particular layer in anorganic light emitting device may be used in combination with a widevariety of other materials present in the device. For example, emissivedopants disclosed herein may be used in conjunction with a wide varietyof hosts, transport layers, blocking layers, injection layers,electrodes and other layers that may be present. The materials describedor referred to below are non-limiting examples of materials that may beuseful in combination with the compounds disclosed herein, and one ofskill in the art can readily consult the literature to identify othermaterials that may be useful in combination.

Various materials may be used for the various emissive and non-emissivelayers and arrangements disclosed herein. Examples of suitable materialsare disclosed in U.S. Patent Application Publication No. 2017/0229663,which is incorporated by reference in its entirety.

Conductivity Dopants:

A charge transport layer can be doped with conductivity dopants tosubstantially alter its density of charge carriers, which will in turnalter its conductivity. The conductivity is increased by generatingcharge carriers in the matrix material, and depending on the type ofdopant, a change in the Fermi level of the semiconductor may also beachieved. Hole-transporting layer can be doped by p-type conductivitydopants and n-type conductivity dopants are used in theelectron-transporting layer.

HIL/HTL:

A hole injecting/transporting material to be used in the presentinvention is not particularly limited, and any compound may be used aslong as the compound is typically used as a hole injecting/transportingmaterial.

EBL:

An electron blocking layer (EBL) may be used to reduce the number ofelectrons and/or excitons that leave the emissive layer. The presence ofsuch a blocking layer in a device may result in substantially higherefficiencies, and or longer lifetime, as compared to a similar devicelacking a blocking layer. Also, a blocking layer may be used to confineemission to a desired region of an OLED. In some embodiments, the EBLmaterial has a higher LUMO (closer to the vacuum level) and/or highertriplet energy than the emitter closest to the EBL interface. In someembodiments, the EBL material has a higher LUMO (closer to the vacuumlevel) and or higher triplet energy than one or more of the hostsclosest to the EBL interface. In one aspect, the compound used in EBLcontains the same molecule or the same functional groups used as one ofthe hosts described below.

Host:

The light emitting layer of the organic EL device of the presentinvention preferably contains at least a metal complex as light emittingmaterial, and may contain a host material using the metal complex as adopant material. Examples of the host material are not particularlylimited, and any metal complexes or organic compounds may be used aslong as the triplet energy of the host is larger than that of thedopant. Any host material may be used with any dopant so long as thetriplet criteria is satisfied.

HBL:

A hole blocking layer (HBL) may be used to reduce the number of holesand/or excitons that leave the emissive layer. The presence of such ablocking layer in a device may result in substantially higherefficiencies and/or longer lifetime as compared to a similar devicelacking a blocking layer. Also, a blocking layer may be used to confineemission to a desired region of an OLED. In some embodiments, the HBLmaterial has a lower HOMO (further from the vacuum level) and or highertriplet energy than the emitter closest to the HBL interface. In someembodiments, the HBL material has a lower HOMO (further from the vacuumlevel) and or higher triplet energy than one or more of the hostsclosest to the HBL interface.

ETL:

An electron transport layer (ETL) may include a material capable oftransporting electrons. The electron transport layer may be intrinsic(undoped), or doped. Doping may be used to enhance conductivity.Examples of the ETL material are not particularly limited, and any metalcomplexes or organic compounds may be used as long as they are typicallyused to transport electrons.

Charge Generation Layer (CGL)

In tandem or stacked OLEDs, the CGL plays an essential role in theperformance, which is composed of an n-doped layer and a p-doped layerfor injection of electrons and holes, respectively. Electrons and holesare supplied from the CGL and electrodes. The consumed electrons andholes in the CGL are refilled by the electrons and holes injected fromthe cathode and anode, respectively; then, the bipolar currents reach asteady state gradually. Typical CGL materials include n and pconductivity dopants used in the transport layers.

As previously disclosed, OLEDs and other similar devices may befabricated using a variety of techniques and devices. For example, inOVJP and similar techniques, one or more jets of material is directed ata substrate to form the various layers of the OLED.

A print head of a conventional OVJP tool generally includes amicronozzle array contained within a silicon die, with a metal clampsurrounding it. FIG. 3 shows an example of such a device. In thisconfiguration, the sides of the clamp 301 compress the die 302 and holdit in place. Organic vapor is fed into and/or drawn from the micronozzlearray through one or more vias 303 on the flat surface of the die, whichare in fluid communication with machined channels 304 on one or bothfaces of the clamp, as shown. The faces of the clamp 305 may be groundand polished to minimize leakage of gas between the faces of the clampand the faces of the die. However, this is not always sufficient toproduce an acceptably fluid-tight seal. In some cases, the faces mayalso be machined with glands for use with elastomeric O-rings 306 orsimilar structures. These may create a better seal than the machined andpolished faces alone, but concerns about outgassing and thermaldegradation of the gasket material generally limit the usefulness ofO-rings in OVJP and other applications, especially for use infabricating organic devices as disclosed herein. Deformable metalgaskets may be used in place of the elastomeric O-rings. However, suchgaskets typically are not commercially available at the scale needed forOVJP and similar deposition systems. Furthermore, even if or when suchgaskets are available, a conventional metal gasket generally wouldrequire a high sealing pressure that would be likely to damage the MEMSdie.

It has therefore been found that designing an interface for micronozzlearrays used in OVJP and similar systems presents unique challengesbeyond those normally encountered when integrating microfluidiccomponents into larger systems. Specifically, the interface that joinsthe silicon die containing the OVJP or other micronozzle array to asource of organic vapor or other material to be deposited on a substrateshould be capable of forming a gas-tight seal at temperatures of up to350 C, without outgassing when subjected to operational temperatures inthat range for potentially long periods of time.

To address these needs, embodiments disclosed herein provide techniquesand devices for sealing a die containing microfluidic elements to ametal manifold, which may be suitable for use in fabricating OVJP nozzleblocks and other devices for deposition of materials on a substrate.According to embodiments disclosed herein, a gasket may be formed on theflat face of a die by depositing traces of ink, which contain metalparticles in suspension, in one or more closed contours around one ormore regions to be sealed to a manifold. A variety of printingtechniques may be used to generate the traces. After the traces aredried and/or sintered, they may provide a deformable metal gasketcapable of sealing the die and manifold, while also withstandingrelatively high temperatures without outgassing.

An example of a gasket pattern trace according to an embodiment is shownin FIG. 4A. Prior to installation of a die into an associated clamp,such as die 302 and clamp 301 shown in FIG. 3, a pattern of a desiredgasket is drawn on a face of the die using an ink that forms a metaldeposit upon drying and/or firing. In this example, the trace includes aclosed contour 401 that is wide enough to enclose both the vias 402 onthe die as well as the channels on the face of the clamp manifold towhich the die is to be attached that correspond to the vias 402. Themetal-containing ink may be deposited by a variety of methods includinginkjet processes, screen printing, and the like. Ink-containing noblemetals like silver and gold typically are preferred, because noblemetals are both soft and chemically non-reactive, though alloys andother materials also may be used. The ink is often a suspension ofmetallic nanoparticles in an organic solvent. After deposition on thedesired trace or traces, the metal-containing ink may be baked orotherwise processed to evaporate the solvent in the ink, leaving behindthe desired metal gasket. Alternately or in addition, a solution oforganometallic precursors that react to leave a metal film may be usedas the metal-containing ink instead of a suspension of metalnanoparticles.

The metal gasket may be considered to be “non-removably” attached to thedie. That is, it may not be possible to remove the gasket from the diewithout damaging the die or causing modifications that would require thedie to be refurbished before being used again with the same or adifferent manifold. Similarly, it may be unlikely or impossible for thegasket to move on the surface of the die between deposition on the dieand placement of the die relative to the manifold.

Once the metal gasket is set on the face of the die, a seal may beformed by compressing the die with the clamp. A schematic view of suchan arrangement is shown in cross-section in FIG. 4B. The metal gasket403 may be wetted to the die at its base 404. The opposite surface ofthe thickest portion of the gasket may deform slightly due to pressurefrom the clamp. The thin, soft metal of the gasket provides a sealbetween the surfaces of the die and the clamp that requires relativelylittle pressure. Due to the presence of the metal gasket, gas or otherfluid materials can be exchanged between vias on the die and a manifoldof channels inside the clamp without leaking into the surroundingenvironment.

In contrast to the non-removable attachment of the gasket to the die,the gasket (and thus the die) may be removably attached to the manifold.The gasket may be considered “removably” attached when it is possible toremove the gasket from the manifold without damaging the manifold, orotherwise requiring refurbishment or modification of the manifold afterremoval of the die before it is used with a subsequent die. In somecases, the gasket (and therefore the die) may be removed from themanifold merely by removing the compressive force used to attach thegasket and die to the manifold. Accordingly, embodiments disclosedherein may be used in devices and systems where the die is considered aconsumable or semi-consumable component.

In an embodiment, multiple banks of one or more vias may be enclosed inseparate and non-intersecting metal contours so that they are sealedboth from each other and the environment around the joint between thedie and the manifold. An example of such a layout is shown in FIG. 5. Inthis example, a first contour 401 of printed metal surrounds a firstbank of vias 402 as previously disclosed. A second contour of printedmetal 501 similarly surrounds a second bank of vias 502.

In some embodiments, printed metal traces may not be closed contours.For example, one or more metal traces may be placed so as to distributeforce from the clamp, improve heat transfer between the die and clamp,or serve similar purposes that may not require surrounding one or morevias between the die and the manifold. For example, a wide line ofprinted metal 503 may be placed along a lower edge of a die 504 where amicroarray of depositors is located. The line of gasket material mayimprove heat transport to the die and/or provide additional mechanicalstability. Such a line may be deposited at the same time as one or morecontours that surround vias in the die, allowing for greatermanufacturing and assembly options and efficiency.

In some embodiments, multiple concentric contours of gasket material maybe used to create redundant seals around one or more vias. An example ofsuch an arrangement is shown in FIG. 5B, where multiple,non-intersecting metal traces 510, 511 surround a single set of vias515.

In some embodiments, multiple overlapping traces may be used. Such aconfiguration is shown in FIG. 5C. In this arrangement, three sets ofvias 517, 518, 519 on the die 504 are surrounded by various combinationsof two traces 520, 522 that form two separate but overlapping gaskets.Vias 517 and 519 are surrounded only by one trace 520, 522,respectively, while vias 518 are surrounded by both traces 520, 522. Thetraces 520, 522 overlap as shown. Such configurations may be desirable,for example, when different combinations of metal-containing inks, tracethicknesses, metals, gasket thicknesses, or other process parameters aredesired. Such configurations also may be desirable where traces areintended to serve multiple purposes, such as providing various gasketarrangements as well as structural enhancements as disclosed withrespect to FIG. 5A. More generally, any combination of overlappingand/or non-overlapping traces may be used to form any desiredarrangement of gaskets or structural components. Similarly, any desirednumber or arrangement of vias may be surrounded by any desired number orarrangement of traces and corresponding gaskets.

Although the examples in FIGS. 5A-5C show uniform traces, any shape orarrangement of one or more traces may be used to form the gasketsdisclosed herein. That is, traces may be rectangular, oval, circular,elliptical, or any irregular shape. The specific shape for a particulartrace may be selected based upon the arrangement of vias the trace isintended to surround, ease of deposition, and/or structuralconsiderations as previously disclosed.

Any trace arrangement, including those such as described with respect toFIG. 4 and FIGS. 5A-5C, may be used to form a device that includes a dieand a metal manifold as shown in FIG. 4B. That is, aftermetal-containing ink is deposited on a trace (or traces) around one ormore vias to form a gasket on the die, the gasket may be placed indirect physical contact with the metal manifold to which the die is tobe sealed. The die is then compressed against the manifold, forming asealed connection between the die and the manifold and, morespecifically, a sealed connection between the via(s) and correspondingchannels in the manifold.

Additional steps may be added to this basic process as desired ornecessary for a specific application, or to achieve specific processparameters. For example, mechanical properties of the gasket may beimproved by sintering. As a specific example, sintering of gold orsilver nanoparticles tends to occur at relatively low temperatures below300 C, so it is a likely side effect of any post-deposition bakeprocess. Sintering may make the gasket more malleable and ductile sothat it performs more like a conventional metal gasket. Sintering alsomay reduce the porosity of the gasket and therefore slow the rate atwhich material can diffuse through it. The sintering may be performed inany suitable environment or atmospheric conditions, including a vacuumor partial vacuum, an inert gas atmosphere, a reducing atmosphere, or anoxygen-containing atmosphere.

As another example, one or more thin films may be deposited on thesurface of the die prior to printing the gasket. This may promoteadhesion between the die and the gasket material. As a specific example,organic materials such as HMDS may be used to clean the surface andmodify its surface energy, which improves adhesion during the initialwet printing process. As another example, evaporated titanium orchromium films may be used as adhesion layers between noble metals and asilicon substrate. Such metals readily oxidize, so it may be desirableto cap or otherwise coat such films with a noble metal prior to printingthe gasket material. The printed gasket material then may bond to thislayer as it sinters. An example of such a structure is shown in FIG. 6.The Si die 601 forms the substrate of the structure. An adhesion layer602 and a capping layer 603 may be deposited over the substrate, such asby e-beam evaporation or any other suitable technique. The adhesionlayer may include, for example, a layer of 200 Å Ti. The capping layermay include, for example, a 500 Å Au layer. A metal trace 604 aspreviously disclosed may then be deposited over the capping layer by aninkjet nozzle 605. The trace layer may include, for example, a 10 μmthick film of gold nanoparticles in suspension.

As another example, the metal-containing ink formulation may containflux that reacts with oxides when heated to ensure a sufficient bondbetween the die and the gasket metal. Fluxes may attack native oxides onthe substrate directly or they may require an additional adhesion layer.Activation of such fluxes generally requires temperatures higher thanthose typically used for sintering processes. Sintering may then beperformed in a vacuum or an inert gas atmosphere to inhibit oxidation. Areducing atmosphere containing forming gas may also be used. Conversely,oxygen may be desired to ash surfactants present in the metal particlesuspension. Thermal treatment of the metal gasket may be done inmultiple steps under multiple types of atmosphere. Thermal processing isnormally done between deposition of the gasket and installation of thedie in the clamp.

In some embodiments, topographic features may be added to the face ofthe clamp to enhance sealing. For example, a pointed or convex surface701 may act as a knife edge to create a seal by creating a narrowdeformation in the gasket 702 as shown in FIG. 7A. If the “knife edge”is sufficiently narrow or shallow, the arrangement may not createexcessive stress on the die material underlying the gasket. Alternately,an indented feature 703 similar to an O-ring groove may be used instead,as shown in FIG. 7B. In some embodiments, printed metal gasket tracesalso may be deposited on the face of the clamp in addition to those onthe die.

Embodiments disclosed herein differ from conventional die attachmentmethods in which solder may be printed on one of two components to bejoined because the solder must wet to both sides of the assembly in dieattachment, oven brazing, or similar techniques. In contrast, inembodiments disclosed herein each printed metal gasket only adheres toone of the two components, and is sealed to the mating surface of theopposite part by compression only. For example, in the embodimentspreviously disclosed, the printed metal gasket is only attachedinitially to the die and may be readily removed from the manifold bysimple removal of the compressive force used to attached the die andgasket structure to the manifold. Accordingly, the resulting joint canbe readily assembled and disassembled.

Embodiments disclosed herein may allow for extremely precise placementof metal gaskets because the gasket material is deposited directly onthe die and, in general, is not subject to movement relative to the diebetween deposition and joining of the die to the manifold. As a specificexample, embodiments disclosed herein may allow for placement of thegasket to within an accuracy of 10 μm or less. In contrast, conventionaltechniques often are relatively inaccurate due to potential movement ofthe gasket between placement and joining of the die and the manifold.Notably, embodiments disclosed herein may achieve this high accuracyeven without the use of a pre-machined groove in the die or similarstructure, since the gasket may be deposited non-removably directly onthe die.

Embodiments disclosed herein also may allow for extremely thin gasketsthat would not be achievable using conventional techniques. For example,gaskets as disclosed herein may be 1000 μm, 500 μm, 200 μm, 100 μm, 50μm, 30 μm, or less in thickness. Any thickness gasket may be createdusing the techniques disclosed herein, up to the roughness tolerance(s)of the components being connected (e.g., the die and the manifold).Conventional techniques typically require much thicker gaskets or othercomponents. For example, many conventional elastomeric O-rings andsimilar components would not be usable at the scales enabled byembodiments disclosed herein, as they would be damaged or destroyedduring any placement process. As a specific example, a 100 μm O-ringlikely would be torn or otherwise damaged by any device that attemptedto place and hold the O-ring in place against a silicon die due to thethinness of the O-ring.

Embodiments disclosed herein also may eliminate more impurities, and mayeliminate them more easily, than conventional techniques may achievesince they do not require other contact with the gasket. Once a gasketis printed on a die as disclosed herein, it may be non-removablyattached to the die and thus may not shift in position on the die as thedie is manipulated. In contrast, conventional O-rings and similarcomponents are likely to shift, and therefore require movement beforethe die is attached to the manifold. Such additional placement is likelyto introduce impurities, for example due to handling of an elastomericor metal O-ring.

Embodiments disclosed herein may be usable in environments and systemsthat are not suitable, or less than well-suited, for the use ofelastomeric or metal O-rings or similar gaskets. For example,embodiments disclosed herein may be particularly well-suited forhigh-temperature applications as previously disclosed, in whichelastomeric O-rings would degrade or fail. Conventional metal gasketssuch as C-rings and compression gaskets, while suitable for use in somehigh-temperature environments, often are not suitable for MEMS-typedevices such as OVJP nozzle blocks, in which a silicon or silicon-baseddie is used.

While embodiments and examples provided herein are described withrespect to illustrative OVJP uses, the scope and content of theinvention is not so limited. Embodiments disclosed herein may be appliedmore generally to any applications that require or benefit from anon-outgassing, high temperature seal between consumable and reusablecomponents. A metal gasket may be printed on the consumable component asdisclosed herein, allowing it to seal to a permanent part of an assemblyon installation and then be easily removed and replaced when needed aspreviously disclosed.

EXPERIMENTAL

Metalon™ JS-B40G silver inkjet metal-containing ink provided byNovacentrix (Austin, Tex.) was used to fabricate and examinearrangements disclosed herein. Silver loading was 40% by weight. It wasdispensed with a Fujifilm Dimax inkjet printer. The die was baked for 1hr on a hot plate at 300 C after printing. All processing was done in anN2 glovebox with O2 and H2O concentrations of less than 10 ppm.

A dimensioned drawing of a die containing a micronozzle array is shownin FIGS. 8A and 8B. FIG. 8A shows the die with two discrete banks ofvias, 801 and 802. The regions around the array available for gasketprinting 803 are identified in FIG. 8B.

FIG. 9 shows a pattern of metal printed on an experimental die 901. Twoclosed rectangular contours 902, 903 of 15 mm in width and 7 mm inheight were printed. The lines of gasket material are 0.25 mm in width.The height of the gasket is defined as the maximum thickness of theprinted material measured perpendicular to the trace by a stylusprofilometer. The height was measured at 6 equidistant points aroundeach of the two contours. The measured values at each measurement pointare shown on FIG. 9 in microns. The average thickness of the gasketmaterial is 6.44 μm high with a standard deviation of 0.22 μm. Therelatively small variation in height indicates that the gasket can bereadily compressed to provide a uniform seal. The RMS roughness of thegasket surface is 95 nm.

An example of a cross sectional profile from a printed seal is plottedin FIG. 10. The horizontal axis 1001 gives distance along an axisperpendicular to the trace and the vertical axis 1002 gives thickness,both in microns. The main body of the seal is 250 μm wide 1003, withthinner shoulders of 50 to 100 μm in width on each side. The height ofthe gasket, as indicated by the thickest point 1004 is 6.88 μm. Printingmay be performed in multiple passes and/or dithered in a directionorthogonal to the trace to control the height and thickness profile ofthe gasket.

It is understood that the various embodiments described herein are byway of example only, and are not intended to limit the scope of theinvention. For example, many of the materials and structures describedherein may be substituted with other materials and structures withoutdeviating from the spirit of the invention. The present invention asclaimed may therefore include variations from the particular examplesand preferred embodiments described herein, as will be apparent to oneof skill in the art. It is understood that various theories as to whythe invention works are not intended to be limiting.

We claim:
 1. A device comprising: a die comprising one or more vias; ametal gasket disposed on and non-removably attached to a surface of thedie around the one or more vias, the metal gasket comprising a metaldeposited via a metal-containing ink; and a metal manifold; wherein thegasket removably connects the die to the metal manifold.
 2. The deviceof claim 1, wherein the gasket forms a closed contour around the one ormore vias.
 3. The device of claim 1, wherein the die comprises aplurality of vias including the one or more vias.
 4. The device of claim1, further comprising a plurality of non-intersecting metal gasketsincluding the metal gasket.
 5. The device of claim 4, wherein eachgasket of the plurality of non-intersecting metal gaskets forms acontour around at least one of the plurality of vias.
 6. The device ofclaim 1, wherein the die is removable from the metal manifold by removalof a compressive force.
 7. The device of claim 1, wherein the diecomprises silicon.
 8. The device of claim 1, wherein the metal gasket isformed from a plurality of traces of the metal-containing ink and atleast two of the plurality of traces intersect.
 9. The device of claim1, wherein the metal-containing ink comprises a compound selected fromthe group consisting of: a suspension of metallic nanoparticles in anorganic solvent; and a solution of organometallic precursors.
 10. Thedevice of claim 9, wherein the metal-containing ink comprises at leastone metal selected from the group consisting of: silver, gold, copper,titanium.
 11. The device of claim 1, wherein the gasket has a thicknessof not more than 100 μm.
 12. A method of connecting a first component ofa device to a second component of a device, the method comprising:depositing a metal-containing ink on a first component of a device toform a gasket; placing the gasket in direct physical contact with asecond component of a device to which the first component is to beattached; and applying a compressive force to the first componentagainst the second component to form a sealed connection between thefirst component and the second component.
 13. The method of claim 12,wherein the first component is removable from the second component byremoving the compressive force.